Valves used in the exhaust gas system, and in particular exhaust gas recirculation valves, serve to reduce exhaust gas emissions. Exhaust gas quantities adapted to the respective operating condition of the internal combustion engine are thereby recirculated into the cylinders of the internal combustion engine to reduce the pollutant constituents, in particular nitric oxides. The exhaust gas recirculation valves typically comprise an actor which is currently most frequently an electromotive actor that is most often operatively connected with a valve rod via a transmission, the valve rod being guided by a guide bushing in a housing of the valve and which has at least one control body at its end opposite the actor, which control body corresponds to a corresponding valve seat between an exhaust gas inlet and an exhaust gas outlet. Most exhaust gas recirculation valves are configured so that, in the closed state of the valve, the valve rod, as well as the transmission and the actor, are arranged in the area containing fresh air and are separated from the exhaust gas side by the control body. When the valve is opened, i.e., when the control body is lifted from the valve seat, hot exhaust gas flows towards the intake pipe so that so that the hot exhaust gas is in communication with the transmission housing. The thermal load on the actor thereby increases, which is the reason why exhaust gas valve devices have become known wherein a thermal separation of the housing, through which gas flows, from the actor is effected by a coolant channel via which heat is dissipated from the exhaust gas.
Such a valve is, for example, described in DE 103 44 218 A1. The valve described therein comprises a valve rod adapted to be actuated by an actor, the valve rod having a valve plate that controls a flow cross section. A coolant channel is formed in the flow housing radially around the valve rod, which channel is open to the actor housing and is closed by placing the actor housing thereon. The connecting nozzles are pressed into corresponding receptacles of the flow housing.
JP 07-233762 A further describes an exhaust gas recirculation valve which is adapted to be operated by a stepper motor, wherein the electric motor is surrounded by a coolant channel in the actor housing. The connecting nozzles for coolant supply are in this case also threaded or pressed into correspondingly formed holes.
These previously described exhaust gas recirculation valves generally either provide for heat dissipation from the actor, without, however, restricting the penetration of heat into the actor housing, or they provide for a mere thermal separation via the coolant channel so that heat once present in the actor cannot be sufficiently dissipated. An increased assembly effort also exists because the connection to the coolant circuit of the internal combustion engine must be effected via connecting nozzles that must be assembled separately because they cannot be realized in known cast housings.